The field of this invention is pipe assemblies and pipelines.
Pipelines in which heating elements or other thermal control apparatus are incorporated find many applications and frequently must be employed where freeze protection or thermal process control functions are to be accomplished in a pipeline.
In the past, pipelines having conduits attached to a pipe and heating elements disposed in the conduits were available. The conduit was attached to the pipe and the pipeline was insulated at the installation site. These installation operations in the field necessitated transporting large amounts of material, equipment, and manpower to the field. The installation operations were frequently performed under disadvantageous circumstances, resulting in high installation cost and sometimes poorly insulated pipelines.
Other pipelines had a permanently affixed heating element on the pipe. The heating elements were attached to the pipes at the installation site, and the pipelines were insulated after the heating elements had been affixed to the pipe. In addition, since the heating element was permanently affixed to the pipe, the heating element could not be replaced without difficulty and possible damage. Further, where such pipelines were buried underground, the pipeline had to be at least partially uncovered before the task of replacing the heating element could even begin.